Structural insulated panel for building construction

ABSTRACT

A structural insulated panel (SIP), such as 8 foot×24 foot, is made with a foam plastic core, oriented strand board on each face, and structural paper on either side of that, all bonded together. The oriented strand board capped with structural paper provides a particularly strong wall structure. Also, the structural paper provides a finished surface as manufactured. SIP-to-SIP joints are created using an insert sandwiched between end portions of in-line-joined SIP panels.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit under 35 U.S.C. §119(e) of provisionalapplication Ser. No. 61/056,217, filed May 27, 2008, entitled STRUCTURALINSULATED PANEL FOR BUILDING CONSTRUCTION, the entire contents of whichare incorporated herein in its entirety.

BACKGROUND

The present invention relates to structural insulated panels such as forbuilding exterior walls, and building structures using same.

Structural insulated panels (SIPS) have been around for a number ofyears. In the 1950's until about 1980, panels were made 4 feet wide andup to 12 feet long with commodity plywood and other materials. Some ofthese panels have finishes that were acceptable as exterior wallsurfaces. The most common was a plywood pattern called reverse board andbatten or sometimes T 1-11 ply. The inside of that was a material suchas drywall or plywood. The center of these panels was plastic foam tocomplete a SIP panel.

The SIP panels discussed above were largely superseded when orientedstrand board (OSB) became available in 8 foot by 24 foot sheets. The 4foot wide panels were too costly and inefficient to install when one bigpanel could replace six small 4-foot-wide panels. However, a problemwith this big 8 foot by 24 foot panel was that it did not have afinished surface on the inside nor outside, since OSB does not provideit. Thus, the big panels were usually covered with drywall on the insideand covered with exterior siding on the outside. Unfortunately, thisprocess of covering inside and outside surfaces after building/wallconstruction is very expensive and made construction with SIPs moreexpensive than conventional “stick” construction. Even though SIPconstruction could save 30% to 50% of the heat loss, there has beencontinued resistance to use the SIP systems because of costs of materialversus “stick” construction.

SUMMARY OF THE PRESENT INVENTION

One aspect of the present invention is a structural insulated panel madewith a foam plastic core and oriented strand board attached on eitherside to form board faces. The oriented strand board faces are cappedwith a structural paper that provides a finished surface. The core, OSBand structural paper are all securely bonded together.

Another aspect of the present invention is a “frameless” building whereexterior walls are constructed primarily using structural insulatedpanels.

In another aspect of the present invention, a building wall includes twostructural insulated panels positioned in-plane and with end edgesadjacent. Each panel includes a foam core, an OSB facer on each side,and structural paper on each side. Each panel also includes an endportion with OSB facer extending beyond an outer surface of the foamcore to define a cavity and an insert positioned between the endportions and extending into the cavity. The insert includes a foam coreand OSB facer on each side, the OSB facer on the insert fitting insidethe OSB facer on the panels; and fasteners fastening each panel to theinsert.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a structural insulated panel (SIP)embodying the present invention.

FIGS. 2-4 are perspective, side, and front views of a partiallyconstructed building.

FIG. 5 is a cross section taken along line V-V in FIG. 4.

FIGS. 6-9 are cross-sectional views showing various joints in anexterior wall of the building, including FIG. 6 showing anexterior-wall-to-roof-beam joint, FIG. 7 showing anexterior-wall-to-floor joint, FIG. 8 showing a SIP-to-SIP joint, andFIG. 9 being an exploded view of FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The illustrated structural insulated panel (SIP panel) is large in size,such as 8 foot by 24 foot, and further incorporates outer layers forminghigh grade exterior and interior finishes as manufactured. The largesize reduces on-site construction costs, and the exterior and interiorfinishes reduce on-site finishing costs. As a result, the present SIPpanels reduce the overall cost of total building construction, so thatthe completed cost is less expensive than “stick” construction (e.g.,wood stud framing for “framed” buildings having an on-site added outsidesuch as vinyl siding and an on-site added inside such as drywall). Thepresent SIP panels also save up to 50% of the heating and cooling costs,as well as meet fire code regulations.

This invention applies a finish in the factory to these large SIPpanels. A combination of changed factors and upgrades of materials withthe oriented strand board (OSB) and structural insulated paper makes fora panel finished inside and out.

-   -   1. The OSB supplied is a higher grade that has minimum edge        swell so that it is more suitable for exteriors, and its        thickness is selected for functional requirements of the        application of use. For example, the OSB thickness can be ¼″ to        ¾″, or more typically about ⅜″ to ½″.    -   2. The OSB is treated and has a high degree of fire resistance        for the inside to help meet building fire codes.    -   3. A structural paper (Kraft) with a polyurethane impregnation        is used to face the OSB. Urethane impregnation of the Kraft        paper is usually from 20% to 35%.    -   4. A waterproof adhesive is used to apply the structural paper        to the OSB. The adhesive is of a fire-resistant type to help        meet building codes. The adhesive penetrates well into the OSB        to prevent delaminations.    -   5. A prime coat of white paint is applied to the structural        paper to make panel more weather-resistant on the outside and        ready for a finish coat on the inside by the owner in the field.    -   6. The outer and inner faces of prime paint, structural paper        and OSB are laminated to both sides of the plastic foam.        (Alternatively, one or both of the prime paint and the        structural paper can be left off one side.)    -   7. The foam is usually an Expanded Polystyrene, Extruded        Polystyrene or Urethane foam plastic. The foam acts as an        insulator and as part of the structure. It can have whatever        foam weight and additives that are appropriate for a particular        application. It is contemplated that expanded foam having a        weight of about 0.8 to 2 pounds per cubic foot, or more        preferably about 1 pound per cubic foot will work well in many        applications.    -   8. The application of the paper to the OSB must be done with        heat and pressure for good bonding. The system can be either        accomplished with a flat bed press or a roller press where the        heat is transferred through the paper very rapidly since it is        very thin. Thickness of the paper is typically 0.011 inches to        0.022 inches.    -   9. The SIP panels can be cut on-site or pre-cut at the factory.

By way of example, structural paper is commercially available and can beused in the present SIP. Some grades of structural paper have a tensilestrength in a machine direction (parallel a longitudinal plane of thepaper) of over 15,000 psi, which is up to about half a tensile strengthof mild steel. When adhered to outside and inside surfaces of an SIParrangement, a strength of the structural paper adds significant beamstrength to the SIP.

FIGS. 2-5 illustrate a “frameless” building construction made using thepresent SIPs in exterior walls. Note FIGS. 6-9 which disclose variousjoint arrangement optimized for the particular SIPs. It is contemplatedthat door and window openings as well as other features (e.g., openingsfor electrical boxes, outlets, switches, utility runs, and the like) canbe pre-cut into the SIPs to reduce on-site construction labor and for amore efficient on-site construction. (FIGS. 2-3, 5 show a circularwindow, but it is contemplated that different window shapes, sizes, andtypes can be accommodated.) Also, components can be added to theprefabricated SIPs, if desired and appropriate, such as final outercolors, windows, hardware, utilities, inter-connectable utility modulesadapted to interconnect between SIP panels, etc.

The illustrated SIP panel (FIG. 1) includes prime paint 1 (such as whiteacrylic), structural paper 2 (such as Kraft paper with urethane impreg),adhesive 3 (such as resorsinal or phenolic), oriented strand board (OSB)4, adhesive 5 (such as urethane), and foam core 6 (such as expandedpolystyrene). The OSB 4 is a facer for the foam core 6. A plurality ofthe SIP panel of FIG. 1 are used to construct the frameless buildingconstruction of FIGS. 2-5. The illustrated building of FIG. 2 includesfour SIP panels for each half of the roof, three for each of thebuilding sides, and three for the floor. However, it is contemplatedthat each roof portion, building side, and floor can be made of one,two, or more SIP panels.

The building (FIG. 3) includes a supporting frame including stilts 10with diagonal cross braces 11, floor joists 12, a window 13 in one end,and roof truss members 15 (see FIG. 5). Pre-manufactured and pre-cut SIPpanels are used to form the floor, walls, and roof. The building can bedesigned with dimensions selected as desired. The illustrated building(FIG. 3) includes exemplary dimensions: D1 of 24′, D2 of 20′-6⅛″, D3 of16′, D4 roof pitch of 12″ run to 6″ rise, D5 floor height of 9′-8⅜″, D6under-floor-joist height of 8′, D7 SIP width of 8′, D8 floor-to-ceilingheight of about 10′-9⅜″, D9 peak ceiling height of 16′-9¾″, and D10window diameter of 5′. Notably, in addition to the window 13, additionalopenings can be made, such as for doors, rectangular windows, channelsfor utility routing, and the like.

FIGS. 6-9 are cross-sectional views showing various joints in a building20 including an outer wall SIP panel 21 and roof SIP panel 22.Specifically, FIG. 6 shows an exterior-wall-to-roof-beam joint 23. Aroof SIP panel 22 is secured to an outer wall SIP panel 21 as follows.The outer wall SIP panel 21 includes a wood 2×4 topper 24 secured to thefoam core 6 of the outer wall SIP panel 21 with a foam sealant 25, andfurther secured by 8d nails 26 (or #14 1½″ staples) that extend throughOSB 4 into sides of the topper 24. Beams of foam sealant 27 provide acontinuous bead bond making a wood-to-wood (i.e., OSB to topper)connection. A beveled (triangular) 2× seat component 28 that provides aminimum bearing of 3 inches for the roof SIP panel 22 on the topper 24and outer wall SIP panel 21. A screw 29 (such as #14 panel screw 1½″)longer than the roof SIP panel 21 is extended through the roof SIP panel21 into the topper 24. The roof SIP panel 22 includes EPS foam core 6and OSB 4 on both sides, but structural paper 2 only on the inside/lowersurface facing the wall SIP panel 21.

FIG. 7 shows an exterior-wall-to-floor joint 30 between an outside wallSIP panel 21 and a floor SIP panel 31. The outside wall SIP panel 21includes EPS foam core 6 and OSB 4 on both sides as well as structuralpaper 2 on both sides of the wall SIP panel 22. A ledger board 32 (e.g.,2×8 wood board) is attached to the outer wall SIP panel 21 by usingscrews 29 (such as #14 panel screw 1½″) longer than the outer wall SIPpanel 21 extended through the outer wall SIP panel 21 into the ledgerboard 32. A second board 33 fits against an end of the floor SIP panel30, and in particular fits between the OSB boards 4 and against the foamcore 6. Several 8d nails 34 (or #14 1½″ staples at 6″ O.C. typical)extend through the OSB boards 4 into the second board 33. Additionalscrews 29 (such as #14 panel screw 1½″) longer than the outer wall SIPpanel 22 are extended through the outer wall SIP panel 22 into thesecond board 33. Adhesive and/or sealant can be used as desired.

FIG. 8 shows a SIP-to-SIP joint 40, and FIG. 9 is an exploded view ofFIG. 8. The joint 40 includes opposing end portions 41 of SIP panel 21(or of SIP panels 22 or 31) and an insert 42. The insert 42 includes afoam core 43 (similar to core 6) and OSB 44 (similar to OSB 4) adheredtogether. A thickness of the insert 42 fits between and inside the OSB 4of the end portions 41 of each SIP panel 21. Beads 45-47 are placedalong an inside of the end portions 41 on the OSB 4 and the foam core 6of each SIP panel 21. The end portions 41 are brought against the insert42, and 8d nails 48 (or #14 1½″ staples) are extended through OSB 4 intosides of the insert 42. The OSB 4 on each side of the SIP panels 21 abut(or are closely adjacent) in inline positions. The illustrated insert 42is about 3¼″ long, such that about 1⅝″ of each end of the insert 42 fitsinto the mating cavity in the end portions 41 of the SIP panel 21.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

1. A structural insulated panel comprising: a foam plastic core andoriented strand board (OSB) attached on either side of the core to formboard faces, the board faces being capped with a structural paper thatprovides a finished surface; the core, OSB and structural paper allbeing securely bonded together.
 2. The structural insulated paneldefined in claim 1, wherein a prime paint is applied to the outer faceof the structural paper.
 3. The structural insulated panel defined inclaim 1, wherein the adhesive used to bond the paper to the OSB iswaterproof and adds to the fire resistance.
 4. The structural insulatedpanel defined in claim 1, wherein the plastic foam core is one ofExpanded Polystyrene, Extruded Polystyrene, or Urethane.
 5. Thestructural insulated panel defined in claim 1, wherein the OSB has addedchemicals to reduce the edge swell and increase the fire resistance. 6.The structural insulated panel defined in claim 5, wherein the OSB is atleast about 2½ inch thick to provide good fire resistance.
 7. Thestructural insulated panel defined in claim 1, where the panel size isvery large, such as 8 foot by 24 foot, to eliminate the need for manysmall panels with numerous junctures.
 8. A building comprising aplurality of the structural insulated panels defined in claim 7, theplurality of panels being attached together to form walls without woodframing, whereby the interconnected arrangement of large panels speedserection of the building, improves building structure, and reducesenergy loss through the building walls once constructed.
 9. Thestructural insulated panel defined in claim 1, where a panelsubstantially forms a structural wall or roof of a building.
 10. Abuilding wall comprising: two structural insulated panels positionedin-plane and end edges adjacent; each panel including a foam core, anOSB facer on each side, and structural paper on each side; each panelincluding an end portion with the OSB facer extending beyond an outersurface of the foam core to define a cavity; and an insert positionedbetween the end portions and extending into the cavity; the insertincluding a foam core and OSB facer on each side, the OSB facer on theinsert fitting inside the OSB facer on the panels; and fastenersfastening each panel to the insert.
 11. The building wall defined inclaim 10, wherein the fasteners include shafts that extend through atleast one of the OSB facers on the insert and through an adjacent one ofthe OSB facers on the panels.